Photoacoustic tomography imaging of biological tissues

Non-invasive laser-induced photoacoustic tomography is attracting more and more attentions in the biomedical optical imaging field. This imaging modality takes the advantages in that the tomography image has the optical contrast similar to the optical techniques while enjoying the high spatial resolution comparable to the ultrasound. Currently, its biomedical applications are mainly focused on breast cancer diagnosis and small animal imaging. In this paper, we report in detail a photoacoustic tomography experiment system constructed in our laboratory. In our system, a Q-switched ND: YAG pulse laser operated at 532nm with a 10ns pulse width is employed to generate photoacoustic signal. A tissue-mimicking phantom was built to test the system. When imaged, the phantom and detectors were immersed in a water tank to facilitate the acoustic detection. Based on filtered back-projection process of photoacoustic imaging, the two-dimension distribution of optical absorption in tissue phantom was reconstructed.